Today's known soccer stadiums have a grass playing field with a standardized size of about 75 m.times.115 m. If necessary the playing field is also provided with a track for light athletic sports. Viewing stands are provided around the playing field and if necessary around the track. Stadiums are also known that are partially covered. Some of the soccer fields have drainage that carries away water during and after heavy rainfall. In individual cases there are also special surface heaters, for example in the Munich Olympic Stadium, so that the field can be played on and used even in winter. The grass can thus be maintained free of snow and ice and relatively dry.
The construction and maintenance of such stadiums are relatively expensive so for commercial reasons there is a need to use these stadiums also for other purposes as for instance for concerts. Above all this subjects the grass surface either directly or through a covering put over it to some damage.
In addition there are multipurpose venues, such as for instance the Dortmund/Westphalia Hall, where the inside surface and the viewing stands are completely under cover. According to use, as for example bicycle races, tennis, team sports, handball, volleyball, or stage shows or concerts, the hall interior is provided with the appropriate ground covering. Nonetheless in the existing European halls the usable inside space is too small to hold a soccer field. A big enough multipurpose hall would not be suitable for a permanent grass covering since the natural conditions necessary (sunlight, rain) are lacking in a closed hall. These requirements can be partially met by an openable or slideback roof. in any case there is the disadvantage that the grass gets damaged when used for certain purposes since it can only be otherwise used for short times. On the other hand grass is only periodically used, for example every two weeks for during the regular soccer season. A solution of this problem can be the use of sod which is set out in strips and rolled up afterward, but such a system is not only expensive, but the sod surface does not bond solidly to the underlying earth and constant removal and reuse quickly kills the grass. The invention is aimed at this problem.